Process of producing sodium aluminate



J. B. BARNITT PROCESS OF PRODUCING SODIUM ALUMINATE Feb. 8 1927.

Filed Jan. 21, 1926 lNl/i'NTOR Patented Feb. 8, 1927.

UNITED STATES PATENT OFFICE.

COMPANY OF AMERICA, 0] PITTSBURGH, PENNSYL PENNSYLVANIA.

ANIA, A' OORPORL'IION OF PROCESS OI PRODUCING SODIUM ALUMHIATE.

Application filed January 21, 1926. Serial No. 32,151.

The invention relates to the dry process production of sodium aluminatefrom the mixture of soda ash and an aluminous ma a dry process terialsuch as bauxite.

It is well known that the commercial value of sodium aluminate dependsalmost entirely upon its content of water-soluble alumina, which in turnis brought about in the dry process production of sodium aluminate byproper calcination of a uniform round mixture of aluminous material ansoda ash. According to prior practice the calcination of this mixture iseffected in either a rotary kiln in which the mixture is tumbled whilebeing heated, or a reverberatory furnace provided with means foragitating the mixture. In both types of furnaces ulverized goal oratomized fuel oil is usual y used as ue V This practice has severaldisadvantages which materially affect the quality of the product and thecost of its production. For example, an inherent characteristic of thepractice is that the agitation of the mixture tends to so fractionate orstratify its ingredients that its intimate nature is destro ed. Thisnecessarily diminishes the extent of reaetion between the ingredientsand correspondingly reduces the water-soluble alu-' mina content andhence the quality of the sodium aluminate. The same ultimate result,namely, the reduction of the watersoluble alumina content of the sodiumaluminate, is brought about and aggravated by dust losses due, amongother causes, to the agitation of the mixture, to a the draft createdby' the products of combustion, and to the evolution of carbon dioxidefrom the dr mass during the reaction.

1) addition to the foregoing, there are further prejudicialcharacteristics of the prior practice which are to a large extentincident to the manner of heating the mixture. In the use of either areverberatory furnace or a rotary kiln it requires from six to twelvehours to complete the reaction, a matter which requires t e consumptionof' a large amount of fuel and adds materially to the operating. cost.Also, it is diflicult to maintain uniform temperatures the mass of themixture, and when the mixture is overheated there results a partialfusion of the soda ash which produces a sticky mass, a segregation ofthe ingredients throughout of the charge, and the formation of sodiumaluminate of inferior quality.

The object of this invention is to provide for producin sodium aluminatewhich overcomes the prejudicial characteristics of the prior rocess, anda process whereby porous sodium aluminate of high' quality and maximumsolubility in water may be economically produced.

The invention is predicated primarily upon my discovery that its statedobjects may be attained "by forming an intimate porous mixture of analuminous material,

soda ash and fuel, and, while the particles of.the mixture are in arelatively quiescent state, rapidly burning the fuel of the mixture.

In the practice of the invention an aluminous material such as bauxiteis first ground to approximately 80 mesh and is then intimately mixedwith soda ash and fuel,soda ash in an amount necessary to effect to themaximum extent the desired reaction, and fuel in the required amount toproduce the necessar heat for effecting the reaction. While variousforms of fuel may be mixed with the reacting ingredients of the mixture,it is preferred to use finely crushed coal or coke or both. Saw dust orshaving may also be used, either alone or mixed with finely crushed coalor coke. When, as preferred, dry finely crushed fuel is mixed with thereacting ingredients, the mixture is preferably moistened with water toabout the consistency of sand when prepared for molding, whichmoistenipg prevents dust losses and renders the mixture sufficientlyporousto permit rapid ignition of the admixed fuel, and to also perm1tthe passage of air and products of combustion through the mass. Afterthe moist intimate mlxture of the reacting ingredients and fuel has beenprepared it is preferably spread on a suitable grate in a layer ofsuitable thickness, say from four to eight inches, and the fuel,preferably at the top side of the mixture is ignited and caused to burnrapidly from its place of ignition through the body or layer of theixture.

It will be understood that the relative proportions of the mixture aredetermined lar ely by the kind ,of aluminous material ant? fuel used. Byway of illustration and not of limitation, I have found a suitablemixture of bauxite, soda ash and finely crushed coal to be in the ratioof 1000 pounds of bauxite containing about 60% aluminum oxide, to 760pounds of soda ash to 340 pounds of finely crushed coal. When the fuelof this mixture is burned in the manner explained, the reaction betweenthe bauxite and soda ash is completed within a period of ten minutes,the mixture being formed in a layer five inches thick. The sodiumaluminate produced by burning the finely crushed coal of this mixturemay have a content of more than 50% of watersoluble alumina and is veryporous and granular.

While the process may be practiced on various forms of apparatus, it maybe advantageously practiced on the well known Dwight and Lloyd type ofore sintering apparatus, one form of which s somewhat diagrammaticallyillustrated 1n the accompanying drawings, of which F 1g. 1 1s acomposite side and vertical sectional view of the apparatus, and Fig. 2a transverse sectional view taken on the line II 1I, Fig 1.

This apparatus comprises a guide consisting of an upper horizontalsection 1, a lower downwardly inclined section 2 and end connecting endsections 3 and 4, the guide forming a track or runway for a lurality ofcars or pallets 5 provided at their sides with rollersfi which rest uponor are engage by the guides. Arranged above and at the right hand end ofthe guide there is a hopper 7 for depositing the mixture on gratebottoms 9 of the cars as they pass beneath the lower end of the hopper.Adjacent to the hopper there are liquid or gaseous fuel burners 8 whichignite the fuel on the upper side of a layer of the mixture as the carscontaining the mixture pass beneath the burners. The cars are movedbeneath the hopper and from the right to the left hand side of the upperguide section 1 by means of a suitable driven sprocket 10 which engagesthe roller 6 of the cars and move them from the lower right hand end ofthe inclined guide section 2 upwardly and u on its horizontal section 1.At the left 0 the burners 8 arranged immediately below guide section 1there is an open top suction box 11 connected by a pipe 12 to a fan orblower 13 for creating a suction or forced draft downwardly through thelayers of the mixture in cars 5.

In the use of this ap aratus sprocket wheel 10 is continuously driven,fan 13 is continuously operated, burners 8 burn continuously and themixture is supplied to the cars as they pass beneath hpper 7 Therotation of sprocket 10 is at such rate of speed that during the timewhich elapses while a car passes from the right to the left end ofsuction box 11 the fuel of the mixture will be entirely burned and thereaction of the bauxite and soda ash completed. The resulting sodiumaluminate then cools as the car moves on guide 1 beyond the left end of.the suction box. When a car reaches guide section 3 it moves rapidlydownwardly and dumps its cooled granular mass in the manner indicated.

In the practice of this process the intimate mixture of the aluminousmaterial and soda ash remains undisturbed, and accordingly there isneither stratification of the ingredicuts of the mixture nor dustlosses. This results in the production of sodium aluminute having a veryhigh content of weter-soluble alumina. The amount of fuel rcquircd fortreating a unit volume of a ITHX- ture of bauxite and soda ash is aboutonelifth that required when sodium aluminate is formed in either arotary kiln or reverberatory furnace, wh ch effects a very large saving.In addition to this improvement in the quality of the sodium aluminateand its lowered cost of production, the sodium aluminate having beenuniformly heated has the further advantageous characteristic of beingvery porous and granular so that its requires no grinding to prepare itfor its various commercial uses or for subsequent refining for theremoval of its alumina content for use in the roduction of aluminum.

While t roughout the specification, and also in the appended claims, theproduct of the process is designated as a porous sintered mass of sodiumaluminate, it will of course be understood that it may contain othercomponents if crude bauxite is used as the sourceof aluminous material,or that it may consist substantially of sodium aluminate if purifiedalumina is used as the aluminous material of the charge.

According to the provisions of the patent statutes, I have explained theprinciple and mode-of operation of my invention, and have given specificdirections of how it may be advantageously practiced. However, I desireto have it understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically described.

I claim:

1.- The process minate, comprising forming an intimate porous mixture ofan aluminous material, soda ash and fuel, and while the components ofthe mixture are in a relative quiescent state rapidly burning the fuelof said mixture to produce a porous sintered mass of sodium aluminate.

2. The process of producing sodium aluminate comprising formin anintimate porous and moist mixture 0 an aluminous material, soda ash andfuel, and while the components of the mixture are in a relativequiescent state rapidly burning the fuel of said mixture to cause otheringredients of producing sodium aluporous and thereof to reactto form aporous sintered mass of sodium aluminate.

' 3. The process of producing sodium aluminate comprising formin anmoist mixture o an aluminous material, soda ash and carbonaceous finelydivided fuel, a (1 while the components of the mixture are in a relativequiescent state rapidly burning the fuel of the mixture to produce aporous sintered mass of sodium aluminate.

4. The process of producing minate, comprising I sodium alutorming anintimate porous and moist mixture of ground bauxite, soda. ash and fuel,and while the components of the mixture are in a relative quiescentstate burning the fuel of said mixture to produce a porous sintered massof sodium aluminate.

5. The process of producing sodium alu -minate, comprising forming anintimate porous and moist mixture of ground bauxite, soda ash and finelydivided carbonaceous fuel, and while the components of the mixture arein a relative quiescent state rapidly burning the fuel of the mixture tocause the other ingredients thereof to react to form a sintered mass ofsodium aluminate intimate having a high content of water-solublealumina.

6. The process of producing sodium aluminate comprising forming anintimate porous and moist mixture of an aluminous material, soda ashandfuel, forming a layer of the mixture upon a grate, and while-thecomponents of the mixture are in a relative quiescent state ignitingsaid fuel at one side of the layer of the fuel to burn rapidly from itssaid place of minate comprising forming an intimate to produce a poroussintered mass of granular sodium alummate. v

7 The process of produc ng sodium alutorming an intimate porous andmoist mixture of granular bauxite, soda ash and carbonaceous fuel,forming a layer of the mixture upon a grate. and while the particles ofthe mixture are in a relative uiescent state i ting said fuel at one sie of the layer 0 the mixture and mixture and causing the causin the fuelto burn ra idly' from its said p ace of ignition throng the body ofthemixture to form a porous of sodiumialuminute.

In testimony whereof, I sign my name.

JESSE BRYTE BABNITT.

sintered mass burning minate, comprising thereof to reactto form aporous sintered mass of sodium alumina '3. The process of producingminate comprising sodium aluformi porous and moist mixture o analuminous material, soda. ash and carbonaceous finely divided fuel, andwhile the components of the mixture are in a relative quiescent staterapidly burning the fuel of the mixture to produce a porous sinteredmass of sodium aluminate.

4. The process of producing sodium aluminate, comprisin forming anintimate porous and moist mixture of ground bauxite, soda ash and fuel,and while the components of the mixture are in a relative quiescentstate burning the fuel of said mixture to produce a porous sintered massof sodium aluminate.

5. The process of producing sodium aluforming an intimate porous andmoist mixture of ground bauxite, soda ash and finely dividedcarbonaceous fuel, and while the components of the mixture are in arelative quiescent state rapidly the fuel of the mixture to cause theother ingredients thereof to react to form a sinteredmass of sodiumaluminate Patent No.1,616,674=.

It is hereby certified that mentioned patent requir ng and insortinstead6 man correction an intimate ite,

JESSE BRYTE BARNIT error a ars in the as follows: Page 3, claim 6,strike out through the body of the having a-high content ofwater-soluble alumina.

6. The process of producing sodium aluminate comprising forming anintimate porous and moist mixture of an aluminous material, soda ash andfuel, forming a layer of the mixture upon a grate, and while thecomponents of the mixture are in a relative quiescent state ignitingsaid fuel at one side of the layer of the mixture and causing the.

fuel to burn rapidly from its said place of minate comprising forming anintimate to produce a porous sintered mass of granular sodium alummate.

7. The process of producing sodium aluminate comprising forming anintimate porous and moist mixture of granular bauxsoda ash andcarbonaceous fuel, forming a layerof the mixture upon a grate, and whilethe particles of the mixture are in a relative uiescent state i nitingsaid fuel at one si e of the layer oi 'the mixture and causin the fuelto burn ra idly fr'om its' said p ace of ignition througi the body ofthe mixture of sodium aluminate.

In testimony whereof, I sign my name.

SE BRYTE BARNITT.

Granted February 8, 1927,11,

of the aboveline to and that the sand printed specification LettersPatent shoul be read with this correctiontherein that the same mayconform to the record of tlisdcafie ipsttfiedPatephOflinie A D 1997 d it is ao are I Slgned an y M. J. Moons,

Acting Commissioner of Patents.

to form a porous sintered mass of Comcfloil. Pam No. 15616574. GrantadFebruary a, 192mm JESSE BRYTE BARNITT. It is hnrb'y certified that errdra ar-in-the printed ofthe moufiomd pnfiqnt cormcti g ns follows: Page 8,claim 6, strike out line40 and thrmlgh the body of 'the'mviartm'a; andthat the said Lem Pitaht ahoul be read with this oorrectmntherein thatthe same may odniorm to the reoni offlm p'ase iu'the Patent Oflice.

Signal and seqled 15th day of Mirch, A. 11. 1am.

am]. M. J. MOORE;

Acting Oomndm'onef of PM.

